A method for calibrating printhead printing deviation of an inkjet printer

Abstract

The present invention relates to a method for calibrating the print deviation of an inkjet printer, comprising: using an inkjet printer to print a print page for calibration; scanning the print page for calibration and performing preprocessing to obtain a print page image; calculating the horizontal angle and the vertical deviation angle of the image; respectively calculating the deviation of all groups of lines in each row of lines, and mapping the vertical deviation angle to the deviation corresponding to the vertically arranged lines and mapping the horizontal angle of the image to the deviation corresponding to the horizontally arranged lines to obtain a final deviation of each group of lines; finally, obtaining an optimal solution for the final deviation of each row of lines, that is, using the optimal solution as the error deviation in each printing mode, and compensating the error deviation in each printing mode for printing by the inkjet printer. This method enables the printer to achieve consistency in control of printing in different directions and speeds, thereby improving the quality of portrait printing.

Description

Technical Field

[0001] The present invention relates to the technical field of inkjet printing, and in particular to a method for calibrating the printing deviation of a nozzle of an inkjet printer. Background Art

[0002] Inkjet printing technology uses a nozzle to spray ink droplets onto a print medium to create images or text. Each nozzle has a fixed number of nozzles, so the height and width of the image printed per scan are limited. To efficiently and quickly produce taller images, the nozzles must be spliced ​​vertically, and the print medium or carriage must be moved forward during printing. However, due to the varying sizes of the nozzles themselves, installation inaccuracies can lead to misalignment between spliced ​​nozzles. This misalignment can seriously impact the quality of printed products. Furthermore, due to the tolerances of the printer's mechanical components, printed images can become misaligned under different printing speeds and directions.

[0003] Therefore, the prior art needs to be further improved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for calibrating the print deviation of the nozzle of an inkjet printer, which can improve the printing quality, in response to the above-mentioned prior art.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a method for calibrating the print deviation of the nozzle of an inkjet printer, characterized by comprising the following steps:

[0006] Step 1: Use an inkjet printer to print out a calibration page.

[0007] The data printed on the calibration page includes:

[0008] Line data, including m OK n Column spacing settings lines; m and n are all positive integers, with the row direction being horizontal and the column direction being vertical; wherein at least one row of lines is horizontally arranged and at least one row of lines is vertically arranged;

[0009] Auxiliary positioning data, including auxiliary positioning lines arranged along the transverse direction of the printing page and second positioning blocks arranged along the longitudinal direction of the printing page;

[0010] Step 2: Scan the printed page used for calibration in Step 1, and pre-process the scanned image to obtain a printed page image;

[0011] Step 3: arbitrarily select multiple points on the auxiliary positioning lines of the printed page image, and calculate the deviation of the mode coordinate difference of the ordinate of each point on the auxiliary positioning lines relative to the abscissa to obtain the angle in the horizontal direction of the image;

[0012] Step 4: Calculate the offset angle in the longitudinal direction of the image based on the edge point coordinates of the second positioning block on the printed page image; Step 5: Calculate the offset angle of each line in the vertical direction of the image. n The deviations of the lines are grouped, and the offset angle in the longitudinal direction of the image is mapped to the deviations corresponding to the longitudinally set lines to obtain the final deviations of the longitudinally set lines; in addition, the angle in the horizontal direction of the image is mapped to the deviations corresponding to the transversely set lines to obtain the final deviations of the transversely set lines;

[0013] Step 6: For each line n The final deviation of the group of lines is optimized to obtain the optimal solution for the deviation of each row of lines;

[0014] Step 7: The optimal solution of the deviation in each line is used as the error deviation in the corresponding printing mode of each line, and the error deviation in each printing mode is compensated in the printing of the inkjet printer.

[0015] To achieve calibration of different printing modes, the line data in step 1 corresponds to at least one or more of the following printing modes when the inkjet printer is printed;

[0016] The printing modes of inkjet printers are: same direction and same speed, same direction and different speeds, different directions and same speeds, and different directions and different speeds. In addition, the same direction and same speed, the same direction and different speeds, different directions and same speeds, and different directions and different speeds are also divided into same color and different colors.

[0017] Preferably, the method for calculating the deviation corresponding to the longitudinal line data printed in the same direction in step 5 is: taking the deviation on the same side as the deviation of each group of lines.

[0018] Preferably, the method for calculating the deviation amount corresponding to the longitudinal line data of the anisotropic printing in step 5 is: taking the deviation of the center line as the deviation amount of each group of lines.

[0019] Preferably, the method for calculating the deviation corresponding to the horizontal line data in step 5 is: taking the deviation of the center line as the deviation of each group of lines.

[0020] Furthermore, in step 6, n The specific steps for obtaining the optimal solution for the final deviation of the group lines are:

[0021] Step 6-1: Count the lines in the current row n The mode of the deviation of the group lines is obtained, and the deviation with the largest number of occurrences is recorded as the first optimal solution;

[0022] Step 6-2: Find the group with the smallest deviation in the current row of lines, and record the value with the smallest deviation as the second best solution;

[0023] Step 6-3: Compare the first optimal solution and the second optimal solution to obtain the optimal solution for the deviation of the current line:

[0024] The specific comparison process is:

[0025] If the first optimal solution and the second optimal solution are the same, the first optimal solution or the second optimal solution is used as the optimal solution for the deviation amount in the current line;

[0026] If the number of line groups corresponding to the first optimal solution differs from the number of line groups corresponding to the second optimal solution by less than one group, the first optimal solution is taken as the optimal solution for the deviation of the current line;

[0027] If the number of line groups corresponding to the first optimal solution exists and the number of line groups corresponding to the second optimal solution differ by within 2 groups, then the average of the first optimal solution and the second optimal solution is taken as the optimal solution for the deviation amount in the current line;

[0028] If the number of line groups corresponding to the first optimal solution does not exist and the number of line groups corresponding to the second optimal solution does not differ by more than 2 groups, the second optimal solution is taken as the optimal solution for the deviation in the current line.

[0029] In order to further improve the accuracy of deviation calibration, step 6 also includes correcting the optimal solution of the deviation corresponding to the multiple lines in the same-direction, different-speed printing mode. The specific correction steps are: determine whether the optimal solution of the deviation of the multiple lines in the same-direction, different-speed printing mode has the same linear relationship with the speed. If so, no correction is required; if not, the optimal solution of the deviation of each line is corrected according to the linear relationship between the speeds of each line.

[0030] In order to prevent the influence of other similar erroneous line images on line calculation and to speed up the calculation time of data calculation, the auxiliary positioning data also includes the following: m First positioning blocks, each first positioning block corresponding to a row of lines, are used to position each row of lines.

[0031] Compared with the existing technology, the advantages of the present invention are: using an inkjet printer to print out a calibration print page, and by scanning the print page and calculating the deviation of each group of lines, the speed and direction tolerances are transmitted to the printer control end to achieve calibration of the printer nozzle direction and speed, so that the printer can achieve control consistency in printing in different directions and speeds, thereby improving the quality of portrait printing and achieving the purpose of nozzle calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a printed page for calibration according to an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a group of lines printed in the same direction according to an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of a group of lines printed in different directions according to an embodiment of the present invention;

[0035] Figure 4 Schematic diagram of a group of lines printed horizontally in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0037] The method for calibrating the print head printing deviation of an inkjet printer in this embodiment includes the following steps:

[0038] Step 1: Use an inkjet printer to print out a calibration page.

[0039] like Figure 1 As shown, the data printed out on the calibration print page includes:

[0040] Line data, including m OK n Column spacing settings lines; m and n are all positive integers, with the row direction being horizontal and the column direction being vertical;

[0041] Auxiliary positioning data, including the vertical arrangement and sequential spacing along the printed page m A first positioning block, an auxiliary positioning line arranged along the horizontal direction of the printing page, and a second positioning block arranged along the vertical direction of the printing page, each first positioning block corresponds to a line; at least one line is arranged horizontally, and at least one line is arranged vertically; Figure 1 As shown, there are two second positioning blocks, which are spaced apart at the top of the printing page. The second positioning blocks also play a role in determining the paper direction of the image;

[0042] In this embodiment, the line data in step 1 corresponds to at least one or more of the following printing modes when the inkjet printer is printed;

[0043] The inkjet printer printing modes are: same direction and same speed, same direction and different speeds, different directions and same speeds, and different directions and different speeds. In addition, the same direction and same speed, the same direction and different speeds, different directions and same speeds, and different directions and different speeds are also divided into the same color and different colors.

[0044] Step 2: Scan the printed page used for calibration in Step 1, and pre-process the scanned image to obtain a printed page image;

[0045] Step 3: arbitrarily select multiple points on the auxiliary positioning lines of the printed page image, and calculate the deviation of the mode coordinate difference of the ordinate of each point on the auxiliary positioning lines relative to the abscissa to obtain the angle in the horizontal direction of the image;

[0046] In this embodiment, the angle in the horizontal direction of the image is obtained by a linear method;

[0047] Step 4: Calculate the offset angle in the longitudinal direction of the image based on the edge point coordinates of the second positioning block on the printed page image;

[0048] In this embodiment, the offset angle can be calculated by using the regression line equation generated by the edge point coordinates of the second positioning block;

[0049] Step 5: Calculate the number of lines in each row n The deviations of the lines are grouped, and the offset angle in the longitudinal direction of the image is mapped to the deviations corresponding to the longitudinally set lines to obtain the final deviations of the longitudinally set lines; in addition, the angle in the horizontal direction of the image is mapped to the deviations corresponding to the transversely set lines to obtain the final deviations of the transversely set lines;

[0050] In this embodiment, the printing direction affects the ink droplet splashing, and the ink droplet splashing cannot be controlled manually and is affected by the printing speed and is generated randomly. Therefore, each set of line data often has good data on one side and poor data on the other side. Figure 2 As shown in the figure, a group of lines are printed in the same direction (the corresponding lines are Figure 1 (in the figure, the line is one of the 13 groups of lines in each row), and the top and bottom of the line are not aligned. For this scenario, the deviation corresponding to the vertical line data printed in the same direction in step 5 is calculated as follows: the deviation on the same side is used as the deviation of each group of lines; Figure 3 As shown in FIG, the calculation method for the deviation amount corresponding to the longitudinal line data of the anisotropic printing is as follows: the deviation of the center line is used as the deviation amount of each group of lines; Figure 4 As shown, since ink droplets splash less when printing horizontally, the deviation corresponding to the horizontal line data is calculated as follows: the deviation of the center line is used as the deviation of each group of lines;

[0051] For each row of lines, since the printing method is the same, the deviations of n groups of lines in each row are calculated using the same deviation calculation method. Then, the offset angle in the longitudinal direction of the image is mapped to the deviation corresponding to the longitudinally arranged lines, thereby reducing the error in the horizontal direction of the calculated deviation. Furthermore, the included angle in the horizontal direction of the image is mapped to the deviation corresponding to the transversely arranged lines, thereby reducing the error in the longitudinal direction of the calculated deviation.

[0052] Theoretically, the optimal solution for the deviation of each group of lines in each row should be the same. However, due to external factors (such as missing line images and severe ink splashing), the optimal solution often fluctuates. Therefore, it is necessary to find the optimal solution for the deviation.

[0053] Step 6: For each line n The final deviation of the group of lines is optimized to obtain the optimal solution for the deviation of each line; that is, to eliminate the error between different prints in the current printing mode;

[0054] Specifically:

[0055] For any line n The specific steps for obtaining the optimal solution for the final deviation of the group lines are:

[0056] Step 6-1: Count the lines in the current row n The mode of the deviation of the group lines is obtained, and the deviation with the largest number of occurrences is recorded as the first optimal solution;

[0057] Step 6-2: Find the group with the smallest deviation in the current row of lines, and record the value with the smallest deviation as the second best solution;

[0058] Step 6-3: Compare the first optimal solution and the second optimal solution to obtain the optimal solution for the deviation of the current line:

[0059] The specific comparison process is:

[0060] If the first optimal solution and the second optimal solution are the same, the first optimal solution or the second optimal solution is used as the optimal solution for the deviation amount in the current line;

[0061] If the number of line groups corresponding to the first optimal solution differs from the number of line groups corresponding to the second optimal solution by less than one group, the first optimal solution is taken as the optimal solution for the deviation of the current line;

[0062] If the number of line groups corresponding to the first optimal solution exists and the number of line groups corresponding to the second optimal solution differ by within 2 groups, then the average of the first optimal solution and the second optimal solution is taken as the optimal solution for the deviation amount in the current line;

[0063] If the number of line groups corresponding to the first optimal solution does not exist and the number of line groups corresponding to the second optimal solution does not differ by more than 2 groups, then the second optimal solution is taken as the optimal solution for the deviation of the current line;

[0064] This step also includes correcting the optimal solution for the deviation of the multiple lines in the same-direction, different-speed printing mode. The specific correction steps are: determining whether the optimal solution for the deviation of the multiple lines in the same-direction, different-speed printing mode has the same linear relationship with the speed. If so, no correction is required; if not, correcting the optimal solution for the deviation of each line according to the linear relationship between the speeds of the lines;

[0065] Step 7: The optimal solution of the deviation in each line is used as the error deviation in the corresponding printing mode of each line, and the error deviation in each printing mode is compensated in the printing of the inkjet printer.

[0066] When the inkjet printer prints in the corresponding mode, each group of deviations is compensated in the printing to improve the image printing quality and achieve the purpose of nozzle calibration.

[0067] For special cases, there are non-optimal solution settings: that is, the target optimal solution is not offset 0. Therefore, the design form of external file input is used to input the specified optimal solution offset to meet the needs of searching for non-optimal solutions in the production process. The specified offset of the optimal solution search can be modified in real time (the default offset is 0).

[0068] Compared to manual calibration, the calibration method in this invention significantly reduces user operations and complexity, and allows for the addition of various calibration data and calibration requirements as required. Compared to other calibration methods on the market, this method incorporates multiple optimal solution calculations and linear calculations between groups, making it less demanding on printhead print quality. This ensures accuracy while reducing the demands on printer hardware. Furthermore, calibration can be completed even in scenarios where some imagery is missing.

Claims

1. A method for calibrating the print head deviation of an inkjet printer, characterized in that The steps include: Step 1: Use an inkjet printer to print out a calibration page. The data printed on the calibration page includes: Line data, including m OK n Column spacing settings lines; m and n are all positive integers, with the row direction being horizontal and the column direction being vertical; wherein at least one row of lines is horizontally arranged and at least one row of lines is vertically arranged; Auxiliary positioning data, including auxiliary positioning lines arranged along the transverse direction of the printing page and second positioning blocks arranged along the longitudinal direction of the printing page; Step 2: Scan the printed page used for calibration in Step 1, and pre-process the scanned image to obtain a printed page image; Step 3: arbitrarily select multiple points on the auxiliary positioning lines of the printed page image, and calculate the deviation of the mode coordinate difference of the ordinate of each point on the auxiliary positioning lines relative to the abscissa to obtain the angle in the horizontal direction of the image; Step 4: Calculate the offset angle in the longitudinal direction of the image based on the edge point coordinates of the second positioning block on the printed page image; Step 5: Calculate the number of lines in each row n The deviations of the lines are grouped, and the offset angle in the longitudinal direction of the image is mapped to the deviations corresponding to the longitudinally set lines to obtain the final deviations of the longitudinally set lines; in addition, the angle in the horizontal direction of the image is mapped to the deviations corresponding to the transversely set lines to obtain the final deviations of the transversely set lines; The line data in step 1 corresponds to at least one or more of the following printing modes when the inkjet printer is printed; The inkjet printer printing modes are: same direction and same speed, same direction and different speeds, different directions and same speeds, and different directions and different speeds. In addition, the same direction and same speed, the same direction and different speeds, different directions and same speeds, and different directions and different speeds are also divided into the same color and different colors. The method for calculating the deviation amount corresponding to the longitudinally arranged lines printed in the same direction in step 5 is: taking the deviation on the same side as the deviation amount of each group of lines; The method for calculating the deviation amount corresponding to the longitudinally arranged lines of the anisotropic printing in step 5 is as follows: the deviation of the center line is used as the deviation amount of each group of lines; The method for calculating the deviation amount corresponding to the horizontally arranged lines in step 5 is as follows: the deviation of the center line is used as the deviation amount of each group of lines; Step 6: For each line n The final deviation of the group of lines is optimized to obtain the optimal solution for the deviation of each row of lines; Step 7: The optimal solution of the deviation in each line is used as the error deviation in the corresponding printing mode of each line, and the error deviation in each printing mode is compensated in the printing of the inkjet printer.

2. The method for calibrating print head printing deviation of an inkjet printer according to claim 1, wherein: In step 6, for any row of lines n The specific steps for obtaining the optimal solution for the final deviation of the group lines are: Step 6-1: Count the lines in the current row n The mode of the deviation of the group lines is obtained, and the deviation with the largest number of occurrences is recorded as the first optimal solution; Step 6-2: Find the group with the smallest deviation in the current row of lines, and record the value with the smallest deviation as the second best solution; Step 6-3: Compare the first optimal solution and the second optimal solution to obtain the optimal solution for the deviation of the current line: The specific comparison process is: If the first optimal solution and the second optimal solution are the same, the first optimal solution or the second optimal solution is used as the optimal solution for the deviation amount in the current line; If the number of line groups corresponding to the first optimal solution differs from the number of line groups corresponding to the second optimal solution by less than one group, the first optimal solution is taken as the optimal solution for the deviation of the current line; If the number of line groups corresponding to the first optimal solution exists and the number of line groups corresponding to the second optimal solution differ by within 2 groups, then the average of the first optimal solution and the second optimal solution is taken as the optimal solution for the deviation amount in the current line; If the number of line groups corresponding to the first optimal solution does not exist and the number of line groups corresponding to the second optimal solution does not differ by more than 2 groups, the second optimal solution is taken as the optimal solution for the deviation in the current line.

3. The method for calibrating print head printing deviation of an inkjet printer according to claim 2, wherein: Step 6 also includes correcting the optimal solution of the deviation corresponding to the multiple lines in the same-direction, different-speed printing mode. The specific correction steps are: determining whether the optimal solution of the deviation of the multiple lines in the same-direction, different-speed printing mode has the same linear relationship with the speed. If so, no correction is required; if not, the optimal solution of the deviation of each line is corrected according to the linear relationship between the speeds of each line.

4. The method for calibrating print head printing deviation of an inkjet printer according to any one of claims 1 to 3, characterized in that: The auxiliary positioning data also includes the following: m First positioning blocks, each first positioning block corresponding to a row of lines, are used to position each row of lines.

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